Paper and process of making the same



Patented Apr. 9, 1929.

UNITED STATE-S 1,708,926 PATENT oF icE;

LESTER xIRScHBRAuN, OF CHICAGO, ILLINOIS, AN ALBERT LQ oLAEP, oE DANVERS,

MASSACHUSETTS; SAID CLAPP ASSIGNOR TO THE ELmTKoTE COMPANY, E Bos- TON, MASSACHUSETTS, A, CORPORATION OF MASSACHUSETTS.

PAPER AND PROCESS or Maxine HE SAME] No Drawing, Application filed February 7, 1.921,

This invention relates to improvements in paper and process of making the same and refers more particularly to the making of waterproof paper in which an adhesive binder, such as asphaltic or bituminous material is incorporated with the paper stock simultaneously with the web forming.

This invention relates to improvements on Letters Patent of the United States issued 0 to Lester Kirschbraun May 6, 1919, No. 1,302,810 and Letters Patent No. 1,536,399, granted May 5, 1925.

Among the salient 0b]GCtS of the invention are to provide a means for precipitating and attaching to the fibres a normally adhesive "bituminous binder in emulsified non-adhesive form; to provide a means whereby the fibrous stock is rendered capable of carrying an extremely large amount of'the bituminous substance in dispersed form; to provide a process in which the. retention of the emulsified bituminous substance during the webforming operation is promoted or improved; to provide a process in which the bituminous material while in dispersed form is so treated that it attaches itself to the fibrous stock rather than becoming lodged upon the wires and blankets of a paper forming machine; to provide a process in which, through the agencyof a bulky precipitant, the dispersed asphalt is enveloped and caused to clot with the fibres in such a manner as to become firmly enn'ieshed therewith or attached thereto; to provide a process in which the bituminous material in its aqueous vehicle is treated w th an agent which causes it to seek contact with the fibrous stock to which the emulsion is added and to cling fixedly with the fibrous material and, in general, to provide a fixing agent by means of which bituminous material may be carried into and by fibrous stock V in relatively large quantities and in a nonadhesive state. I

Adhesive waterproof materials, such as pitches, asphaltic or other bituminous substances, may be emulsified by heating the same to a temperature above that at which they liqucfy, this temperature being ascertained by the melting point of the particular substance to be emulsified, and subsequently combining this liquid adhesive material with an emulsifying agent, such as colloidal clay, in an aqueous vehicle by thoroughly stirring the-adhesive substance and emulsifying sus- Serial No. 443,247. Renewed September 24, 1925.

ension together. As disclosed in the Lotters Patent previously mentioned, an asphaltic emulsion so produced comprises water as the externaphase and asphalt as the internal or disperse phase, the particles of asphalt being protected and-insulated by clay which is adsorbed upon the surface-0f the former.

It is desirable that the emulsion should containits asphalt in the finest possible degree of dispersion, it being found in practice that substantially all of the particles will pass through a screen having 40,000. openings to the square inch with many of the finer particles of such size as to Show Brownian move ment. This process of emulsification is preferably carried on commercially as continuous operation.

It has been the practice heretofore to mix the emulsion so produced with fibrous stock either in the heaters or in the flow box and to run this stock over the paper forming machine to produce a sheet in which the bitumi nous material is carried and incorporated in the sheet during the web-forming operation. Under such conditions it has been found that the asphaltic particles in the emulsion are more or less loosely associated with the fibrous stockso that when run over the machine considerable quantities of the emulsion released from the stock and flowing out with the back water contact heavily with the wires and blankets, the superficial portions thereof having a tendency to become deposited thereon where subjected to pressure and vacuum. Inother words, thewet sheet has insuflicient attraction for the emulsified asphaltic particles to prevent considerable quantitiesof the exposed particles from being carried on to the blankets and wires. While, however, the stock is entirely non-adhesive, the association of those non-adhesive particles with the fibrous stock is insufficient to prevent the loss of considerable quantities of asphalt and to permit the maximum Service of the blankets and wires. Likewise, as the amount of emulsion in non-adhesive form is increased when producing a sheet with a high degree of saturation, a point is reached" when with the increasing amounts of asphalt, the limited carrying capacity of the fibre permits an inordinate loss of emulsified asphalt. The present invention, which involves the use of a fixing agent, as hereinafter described, greatly increases the carrying capacity of with the stock as to eliminate substantially the fibres and causes the emulsified particles to become so strongly attractedand meshed all tendency for it to deposit -on the blanket or. wires'even under heavy; pressure. Thus the formation of the sheet is improved and the ability to run' large quantities of the aspaper ma-" phalt containing stock over the chine is reatly enhanced.

The e ect of the fixing. agent upon the emulsified asphalt particles and the stock is analogousto aclottmg action, in that the articles of dispersed asphalt, clay and bre when in thin aqueous suspension a pear agglomerated, curdled 'or flocculate without turbity of clay and asphalt imrticlcsinthe water, but with the water between the clotted fibre in a comparatively clear state.

- In carrying out the present invention, the

fibrous stock of desired character is chargedto the heater and beaten ut in the usual manstock is added to the b aters a solution of silicate of soda, commo' y. known as water glass. The percentage of ilicate of soda used will, of course, vary with the amount of asphalt to be carried but generally about 1% of concentrated silicate of soda for 10% asphalt to be carried is sufficient.- After the stock is beaten out, the asphalt emulsion, pre-' ner. Together with th%-charge of fibrous pared as described is" pumped to the heaters and a predetermined quantity added to the beaten stock. Durin the charging of the asphalt emulsion, the eater roll is preferably raised to avoidfriction of the knives ,on't'he asphalt. The c onte'nts'of the beater are allowed to circulate until the stock and asphalt are thoroughly mixed together. An excess of aluminum sulphate. is then added either in granulated form or in solution sufiicient to combine with the sodium silicate and, in addition, to produce the clotting action heretofore described. 3 The amount re uire can be determined 'by removing some 0' the treated'stock from the heaters and permitting the water to.

drain away. Suflicient alum is indicated when the drops of water draining from the stock show clear and free from any signs; of

turbidity or asphalt emulsion. A sample of this stock will appear to be clotted and when diluted with water in a bottle or test tube will settle rapidly, leavin the water perfectly clear and showing the brous stock with its contained asphalt uniformly distributed therethrough. When viewed under the microscope, the particles of asphalt seem to be fixedly attached orclothed upon the fibres with a filmy flocculent envelope enmeshing When the stock and emulsion are combined without the use of such afixing' agent, the

' them with the stock, there bei'n comparative- 1y little of the asphalt unattac ed asphaltic particles are rather loosely 'associated with the fibre so that when diluted the asphalt particles are seen to be largely floating in, the water free from-the fibre. VVhenl permitted to stand, such stock does not break clear, but produces a turbid suspension which upon settllng results in a moreor less concenrated la er of asphalt on the fibrous 1a or.

Under t e microscope the particles of asp alt seem to be substantially free and detached from thefibrous stock, whereas the stock of the present invention. when. so viewed shows the asphalt, articles surrounded with a bulky precipitate f aluminum silicate, enclosing the bituminous particles-land clin ing or contacting'with the-fibers'through 518k feathered-like coatings. Y An example of the ing thoroughly asphalt is added to an amount of 1,000 pounds. The asphalt, as explained, is in an aqueousemulsion with its contained described process is as follows: to 1,000 pounds of stock add 35 to pounds of sodium silicate and after beatclay. When this mixture'is completed, there is added ounds of aluminum sulphate which. in com ination .withfthe sodium silicate, gives the effect heretofore described.

In carrying out this process it has been found that in certain instances there is a tendency for the heavyagitation of the beater roll to disturb the clottin effect, both by disrupting-thefilm-like enve opes about the dis 'persed binder and loosening the binder from the contact with the fibres. In such case, we

may treat the emulsified binder by first mixing the emulsion with sodium silicate and then precipitating thesodium silicate with aluminum sulphate, or these reagents may be added to the emulsion in the reverse order and by theaddition to the fibrous stock of. alkali, such as caustic soda, the treatedstock canbe maintained in alkaline condition. on

the other hand, where aluminum sulphate is inedxcess, the condition is, of course, slightly 'ac1 The emulsion so treated may be mixed with I the fibrous stock inthe stufi chest where the agitation is less severe or it may be added to the water withdrawn by the pump from the inside of the-cy1inder.mold, which water is returned to the screens for admixture with the stock. It should be noted that the fixing phate have been mentioned as producing the precipitant giving the desired result, caustic soda may replace sodium isilic'ate,'the proportions being so adjusted in such case as to-propersed state, to deposit in unaltered state and vlde an excess oi alum for the formation of clot vupon the fibrous stock by the addition of aluminum'hy'droxide. We have not as yet.

been able to ascertain if there is'fany generic class of Substances which have the fixing properties described. While generally the fixing agent is a somewhat gelatinous precipitate, nevertheless all precipitates of this nature do 'not have the same properties of strongly attracting the asphalt to thefibres. The well known rosin size, for example, which produces with aluminum sulphate an insoluble soap does not have these fixing properties when used in any reasonable quantities. Other substances which have similar fixing properties are produced by the reaction of zinc sulphate an sodium sulphite; trisodium phosphate and zinc sulphate; metallic perature to which the sheet is subjected sufiicient to soften the asphalt particles and cause them to merge, coalesce, flow through the sheet and adhesively unite with the fibres. In some cases it is desirable to dry the sheet at relatively low temperature so .as to remove the moisture and cause the asphalt to unite with the fibres but without liquefying the asphalt to coalesce the particles.

We claim as our invention:

1. A method of treating fibrous stock containing a bituminous-pitch type base dispersedin an aqueous medium containing a dispersing agent, comprising causing the emulsified base, while maintainingitsdispersed state, to deposit in unaltered state and clot. upon the fibrous stock solely by the addition of reacting inorganic substances.

2: A method of treating fibrous stock containing a bituminous-pitch type base dispersed in .an aqueous medium containing a dispersing agent, comprising causing the emulsified base, while maintaining its dispersed state, to deposit in unaltered state and clot upon the fibrous stock solely by the addition of an inorganic base and an excess of reacting salt.

3. A method of treating fibrous stock containing a bituminous-pitch type base dispersed in an aqueous medium containing a. dispersing agent, comprising. causing the emulsified base, while maintaining its dissilicate of soda and a reacting salt to the mixture;

'4. A method of treating fibrous stock containinga bituminous-pitch type base dispersed in an aqueous medium containing a dispersing agent, comprising causing the emulsified base, while maintaining its dispersed state, to deposit in unaltered state and clot upon the fibrous stock by the addition of silicate of soda and a metallic sulphate to the mixture. I

5. A method of treating fibrous stock for running over a paper machine, comprising mixing the stock with an emulsion comprising a normally adhesive bitumen-pitch type base in a non-adhesive condition in an aqueous medium with an emulsifying agent, and forming bulky aluminum silicate coatings about the particles of emulsified base by the addition of silicate of soda and an exess of aluminum sulphate to the mixture.

6. A method comprising mixing fibrous stock and an aqueous bituminous emulsion in which the bitumen constitutes the dispersed phase, and adding sodium silicate and a metallic sulphate to such mixture to form a fiocculent precipitate of metallic silicate surrounding the particles of dispersed bitumen to cause the bitumen to deposit and clot on the fibres.

7 A process of making waterproof paper comprising mixing fibrous stock with bitumen dispersed in an aqueous medium containing an emulsifying agent, causing the emulsified bitumen, while maintaining its dispersed state, to deposit in unaltered state and clot upon the fibrous stock by adding sodium silicate and aluminum sulphate to form aluminum silicate, and subsequently flowing the stock so prepared over a paper-forming machine'to remove the water, dry the sheet and cause the bitumen to adhesively unite with the fibres. g

8. A process of making waterproof paper comprising mixing fibrous stock with bitumen dispersed in an aqueous medium containing a clay-like emulsifying agent, causing the emulsified bitumen, while maintaining its dispersed stage, to deposit and clot upon the fibrous stock by adding sodium silicate and aluminum sulphate to form aluminum silicate, and subsequently flowing the stock so prepared over a paper-forming machine to remove the water, dry the sheet and cause the bitumen to adhesively unite with the fibres.

9. A process for manufacturing a composite material from pitch and fibrous matreial, comprising mixing together extremely finely divided pitch and fibrous pulp in an aqueous medium, conditioning the product to permit it to be readily felted into sheets solely by the addition of inorganic substances to the mixture said inorganic substances reacting with each other, and felting same on a machine of the paper-making type.

. 10. A process for. manufacturing composite material from pitch and'fibrous material,

medium, conditioning the stock to permit it to be readily felted into 'sheets b sodium silicate and aluminum su phate to the mixture whereby the sodiumsilicate' and aluminum sulphate react with each other, and

feltingjsame on a machine of the pa'per-mak ing type. I V

11. A method which comprlses mixlnghn' Water, fibrous stock, a dispersion of waterproofing material and silicate ofsoda, adding a precipitant incapable of reacting with the waterproofing material and running off on a paper machine.

12. A method of conditioning a mixture of .fibrous stock and finely divided waterproofing material inan aqueous medium, comprising adding to the mixture an morganlc base, and a salt reacting solely with the morganic base to cause the particles of waterproofing y material to deposit and (slot upon the fibrous stock, and then sheeting the mixture on a paper machine.

13. In the method of preparing beater stock, the step which comprises adding a precipitant to an aqueous mixture of fibre, dispersedwaterproofing material and silicate of soda, said precipitant being incapable of reacting with the waterproofing material.

14. In the method of preparing beater stock, the step which comprises-adding an excess of precipitant to an aqueous mixture of fibre, dispersed waterproofing material and an inorganic base, said preclpitant being 1ncapable of reacting with the waterproofing material. r v

15. In the method of preparing stock, the step which comprises adding an excess of recipitant to an aqueous mixture of fibre, dispersed asphalt and an inorganic base, said precipitant being incapable of reacting with the asphalt.

16. A sized fibrous paper-making stock containing dispersed Waterproofing particles fixedly attached to and retained on the fibres,

substantially wholly by a voluminous flocculent insoluble silicate chemically distinct from the waterproofing particles.

17-. A sized fibrous paper-making stock' brought to an acidic condition and containing dispersed waterproofing particles fixedly attached toand retained on the fibres sub stantially wholly by an insoluble inorganic distinct .from the waterproofing particles. I 18. A sized fibrous paper-makingstock containing dispersed asphalt particlesfixedly adding beater 'in'to sheets.

stantially wholly by a voluminous'fiocculent, insoluble silicate uncombined chemically with g the waterproofin particles. comprisingmixing together extremely finely divided pitch and fibrous pulp in an aqueousagent distinct from the silicate.

22. A sized, fibrous paper making stock containing 10 to dispersed asphalt particles fixedly attached to and retained on the fibres substantially wholly by a voluminous,

flocculent, insoluble silicate.

23. A sized fibrous paper making stock brought to an acidic condition-and contain ing 10 to 50% dispersed asphalt particles attached 113i and retained on the fibres, sub

fixedly-atached to and retained on the fib'res substantially Whollyby an insoluble, in-

organic precipitatddistinct from the waterproofing partlcles. I

24. A sized "fibrous paper making stock containing dispersed waterproofing materials fixedly attached to and retained on the fibres by a yoluminous precipitate comprising the reaction product of soluble saltsadded separatelyio the stock.

batch of fibrous stock and a batch of dispersion of a bituminous base in an aqueous medium, one of said batches containing a precipitant in quantities suflicient to produce an acidic condition in the mixture of .fibrous stock and dispersion whereby. to cause the bitumen to 'clot in unaltered state upon the fibers, and running off the mixture on a paper making machine. 1 26. A process for making fibrous sheet maprocess of making waterproofed paper, which comprises bringing together aterial, which comprises mixing a suspension of.beaten fibersand a dispersion comprising solid or'semi-sohd waterproofing material, water and a protective agent 1n alkaline medium, adding arr excess of acidic substance to the mixture, thus causing dispersed water-"' proofing material to be carried onto the fiber. iii-unaltered state and subsequently forming LESTER KIRSCHBBAUI I A ALBERT CLAPP. 

